Physics of shock waves and high-temperature hydrodynamic phenomena - Ya.B. Zeldovich and Yu.P. Raizer (translated from the Russian and then edited by Wallace D. Hayes and Ronald F. Probstein); Dover Publications, New York, 2002, 944 pp., $34.

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

https://iopscience.iop.org/article/10.1088/1361-6463/aaa2f2/pdf

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

In order to control laser-induced shock processes, two main points of interest must be fully understood: the laser–matter interaction generating a pressure loading from a given laser intensity profile and the propagation of induced shock waves within the target. This work aims to build a predictive model for laser shock-wave experiments with two grades of aluminum at low to middle intensities (50 to 500  GW/cm2) using the hydrodynamic Esther code. This one-dimensional Lagrangian code manages both laser–matter interaction and shocks propagation. The numerical results are compared to recent experiments conducted on the transportable laser shocks generator facility. The results of this work motivate a discussion on the shock behavior dependence to elastoplasticity and fracturation models. Numerical results of the rear surface velocity show a good agreement with the experimental results, and it appears that the response of the material to the propagating shock is well predicted. The Esther code associated to this developed model can therefore be considered as a reliable predictive code for laser ablation and shock-wave experiments with pure aluminum and 6061 aluminum in the mentioned range of parameters. The pressure–intensity relationship generated by the Esther code is compared to previously established relationships.

/pdf/numerical-study-of-laser-ablation-on-aluminum-for-shock-wave-23xh56ci0e.pdf

Numerical study of laser ablation on aluminum for shock-wave applications: development of a suitable model by comparison with recent experiments

On improving ballistic limit of bi-layer ceramic–metal armor

The main aim of the present work is to check the suitability of the brittle fracture model, namely the local strain energy density (SED), in predicting the experimental results on mode I fracture of blunt V-notched graphite components. For this purpose, a wide range of test results reported in the recent literature on brittle fracture of V-notched test specimens characterized by different geometries is considered. The specimens are made of the same type of coarse-grained polycrystalline graphite. The fracture assessment is carried out predicting theoretically the fracture loads by means of the SED criterion. The SED parameter is evaluated by averaging the local energy over a well-defined control volume which embraces the notch edge. It is found that the SED criterion allows assessing the fracture behavior of graphite specimens characterized by different notch angles and tip radii.

/pdf/fracture-assessment-of-blunt-v-notched-graphite-specimens-by-nysix98ag1.pdf

Fracture Assessment of Blunt V-Notched Graphite Specimens by Means of the Strain Energy Density

https://hal.archives-ouvertes.fr/hal-01058362/document

Dynamic cratering of graphite: Experimental results and simulations

https://hal.archives-ouvertes.fr/hal-00980178/document

F. Guillet

Papers

Dynamic cratering of graphite: Experimental results and simulations

Penetration and cratering experiments of graphite by 0.5-mm diameter steel spheres at various impact velocities

Dynamic Behavior of a Porous Brittle Material: Experiments and Modeling☆

Simulations of Hypervelocity Impacts into Graphite